Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

drawing/curve_test.go

@@ -0,0 +1,35 @@
+package drawing
+
+import (
+	"testing"
+
+	"github.com/wcharczuk/go-chart/v2/testutil"
+)
+
+type point struct {
+	X, Y float64
+}
+
+type mockLine struct {
+	inner []point
+}
+
+func (ml *mockLine) LineTo(x, y float64) {
+	ml.inner = append(ml.inner, point{x, y})
+}
+
+func (ml mockLine) Len() int {
+	return len(ml.inner)
+}
+
+func TestTraceQuad(t *testing.T) {
+	// replaced new assertions helper
+
+	// Quad
+	// x1, y1, cpx1, cpy2, x2, y2 float64
+	// do the 9->12 circle segment
+	quad := []float64{10, 20, 20, 20, 20, 10}
+	liner := &mockLine{}
+	TraceQuad(liner, quad, 0.5)
+	testutil.AssertNotZero(t, liner.Len())
+}